1. Field of the Invention
This invention relates to a mobile electronic device and, more particularly, to a mobile electronic device and a power management method of a battery module thereof.
2. Description of the Related Art
In an environment that an external power source (such as a commercial power socket) can be used, generally, when a user uses a portable computer, he or she may still habitually connect a power supply to the portable computer, thereby using the power supply to convert external alternating current power to direct current power thus to provide power for the portable computer. In this condition, the user may generally leave a rechargeable battery in the computer, and the portable computer may charge the rechargeable battery.
FIG. 1 is a schematic diagram showing accumulating capacity in a conventional rechargeable battery. That is, FIG. 1 is a schematic diagram showing a curve of changes in capacity of a rechargeable battery of a conventional portable computer. Since a power adapter circuit can charge the rechargeable battery when providing direct current power for the computer, the capacity stored in the rechargeable battery is shown as the curve in FIG. 1. The rechargeable battery is gradually charged from a charging state 101 to a full capacity state 102 and continuously maintains the full capacity state 102.
According to the above method that the rechargeable battery maintains the full capacity state, when the portable computer is carried to the outside, the computer can be operated via the power supplied by the rechargeable battery at once for the longest usable time. However, the above method has negative influence on the lifespan of the rechargeable battery. Usable accumulating capacity of the rechargeable battery has a characteristic. That is, when the actual capacity stored in the rechargeable battery maintains a high level for a time, the usable accumulating capacity of the rechargeable battery may be gradually weakened. Therefore, after a long time, the usable accumulating capacity of the rechargeable battery may reduce to fail to provide the power.
FIG. 2 is a schematic diagram showing weakening changes in the usable accumulating capacity of the rechargeable battery over time. FIG. 2 shows changes in the usable accumulating capacity of the rechargeable battery after the rechargeable batter storing different capacity is not used for one year. According to a first curve 202, if a rechargeable battery maintaining one hundred percent storing capacity is not used for one year, the usable accumulating capacity of the rechargeable battery is weakened to ninety percent of the original usable accumulating capacity.
According to a second curve 204, if a rechargeable battery maintaining forty percent storing capacity is not used for one year, the usable accumulating capacity of the rechargeable battery is weakened to ninety-seven percent of the original usable accumulating capacity.
According to a third curve 206, if a rechargeable battery without storing capacity is not used for one year, the usable accumulating capacity of the rechargeable battery can almost still maintain the original usable accumulating capacity.
According to FIG. 2, the following conclusion can be obtained. The higher capacity stored in the rechargeable battery is, after a period of time, the lower the usable accumulating capacity of the rechargeable battery is.
To improve weakening of the usable accumulating capacity of the rechargeable battery, in the prior art, a user may perform fully discharging operation for the rechargeable battery at regular intervals, such that the whole capacity stored in the rechargeable battery does not maintain a high capacity state, further to maintain the usable accumulating capacity of the rechargeable battery. According to the above method, in one aspect, the user needs to perform the fully discharging operation periodically, which causes inconvenience for the users. In another aspect, the whole charging and discharging times of the rechargeable battery is limited. Although the above method can be used to maintain the whole accumulating capacity of the battery, the remaining charge times of the rechargeable battery is reduced.